Displacement control system for hoist apparatus

ABSTRACT

A displacement control system for hoist apparatus, in which the winch is driven by a drive which is controlled by a pneumatic signal derived from a pressure controller, the controller output pressure signal being determined by comparing in a computing pneumatic relay variable signals derived from a relative motion responsive reference sensor, a load position sensor, and a speed sensor.

United States Patent [191 Barron Aug. 21, 1973 DISPLACEMENT CONTROL SYSTEM FOR HOIST APPARATUS [75] Inventor: Charles D. Barron, Huntington Beach, Calif.

[73] Assignee: Fyron Jackson Inc., Long Beach,

Calif.

[22] Filed: Mar. 25, 1971 [21] Appl. No.: 127,892

Related US. Application Data [63] Continuation-impart of Ser. No. 19,564, March 16,

1970, abandoned.

[52] US. Cl. 254/172 R, 214/14, 137/82 [51] Int. Cl B66d l/48 [58] Field of Search 254/172, 173;

[5 6] References Cited UNITED STATES PATENTS 7/1971 Polyakov et a]. 214/14 X 6/1965 Carl et a1. 254/173 X 3,309,065 3/1967 PrudHomme et a1 254/172 2,946,466 7/1960 Weiner 214/14 2,966,221 12/1960 Kinney 254/173 3,500,764 3/1970 Warman 254/173 3,361,080 1/1968 Born et a1. 254/172 3,482,588 12/1969 Kreuter 137/85 3,181,547 5/1965 Bennett 137/82 Primary Examiner-Richard E. Aegerter Assistant Examiner-Merle F. Maffei Attorney-Donald W. Banner, William S. McCurry and John W. Butcher [5 7] ABSTRACT A displacement control system for hoist apparatus, in which the winch is driven by a drive which is controlled by a pneumatic signal derived from a pressure controller, the controller output pressure signal being determined by comparing in a computing pneumatic relay variable signals derived from a relative motion responsive reference sensor, a load position sensor, and a speed sensor.

2 Claims, 7 Drawing Figures Patented Aug. 21, 1973 3,753,552

5 Sheets-Sheet l INVENTOR CHA @465 0. 5/4 220V Patented Aug. 21, 1973 5 Sheets-Sheet 2 N M R0 5 ma 1% mm M2 mu a 5@ w 0 50 2 WM m7 4 a Fw f a Q 9 WW 3 CW w we Q o e /u M w w I 5 w 7 2 a a 90 M \S I H Patented Aug. 21, 1973 5 Sheets-Sheet 5 QQQ IURBQU WQK WEN INVENTOR (99446665 0 BAEEOA/ i 0.

Patented Aug. 21, 173 3,753,552

5 Sheets-Sheet 5 INVENTOR (H/45465 0 5/4Z!@/V yomj.

DISPLACEMENT CONTROL SYSTEM FOR HOIST APPARATUS This application is a continuation-in-part of United States application Ser. No. 19,564, now abandoned filed Mar. 16, 1970 and entitled Position Sensing Pneumatic Control".

BACKGROUND OF THE INVENTION Problems are encountered when a load is being moved between relatively movable locations by hoist equipment such as a crane. Examples of such relatively movable locations between which a load must be moved include a well drilling barge or platform at sea and a work boat on which equipment and supplies are moved between the barge or platform and shore or the bottom of the sea. In such situations, the drilling platform may be stationary, but the boat will move in a manner and at a rate determined by the rise and fall of the sea. A drilling barge, on the other hand, may be afloat and, thus, also movable, but differently than the work boat or the bottom of the sea.

In either event, however, it is apparent that when a load is being moved by the crane hoist between the barge or platform and the work boat, the relative movement is compound, in the sense that the load, supported by the crane is moving relative to the relatively movable barge or platform and boat. The movement of the load relative to the crane support, i.e., the barge or platform, is at a rate determined by operation of the usual hoist mechanism, but the movement of the load relative to the work boat is a function of the rate of operation of the hoist mechanism modified by relative movement of the work boat, as may be caused by waves effecting alternate rising and falling of the work boat relative to the load. Similar differential movement is encountered when the hoist is on a floating platform.

Therefore, problems are encountered when loads are being moved by the crane or other hoist apparatus to or from a work boat or other relatively movable location, and under severe conditions, the task of moving the load may be rendered impossible, or at least hazardous.

SUMMARY OF THE INVENTION The displacement control system for hoist apparatus, according to the present invention, obviates the problems and hazards attendant to handling loads under the conditions that one or both of the locations between which the load is to be moved is or are also movable.

More particularly, the present invention provides a displacement control system for cranes which relates the relative motion between the locations to and from which a load is being moved by the crane to movement of the load in such a manner that the drive for the crane hoist is adjusted to compensate for uncontrolled movement of, say, a work boat to or from which a load is being transferred from or to a drilling platform or other base for the crane.

The displacement control system, in general, involves a winch adapted to be driven by a power source through a clutch which is capable of slipping, whereby to apply a pre-set tension to the load supporting cable system. The clutch is controlled by sensing the relative movement of the work boat and the crane support or platform to produce a control signal which is proportional to the relative movement, so that the load is moved by or allowed to move in a manner corresponding with the relative movement and therefore remain in a controlled position relative to the moving boat, while moving relative to the crane in the same manner as the boat. With such a system, the load can be lowered or raised relative to the moving boat in a controlled manner enabling the load to be placed on or removed from the work boat without experiencing uncontrolled movement of the boat caused by waves. The system, thus, greatly facilitates loading or unloading loads on or from relatively moving boats or platforms and boats at sea, without damage to the boat or to the load being transferred.

In accomplishing the foregoing, the slip clutch is supplied with air to engage the clutch to transmit torque at a value determined by the magnitude of the air pressure. This air pressure is supplied from a proportional pressure controller, the output pressure from which is determined by sensing changes in position of the load relative to the crane and sensing changes in the position of the moving boat and platform relative to one another, and comparing signals representing the changed positions in a computer device which supplies an output signal to the pressure controller which output signal is a function of the relative load, boat and crane positions. More specifically, the speed of motion of the load is also sensed and supplied to the computer to control the rate of movement change. A bias signal is supplied to the reference sensor to cause change in the position of the load, say to lower the load onto or lift the load from the deck of the work boat, as the system causes the load to also move similarly to the motion of the boat.

Constant tension winches, driven by a fluid pressure actuated slip clutch are well known, as exemplified in United States Letters Patent No. 3,373,972, dated Mar. 19, 1968. Preferably, however, to effect better cooling of the slip clutch with resultant improved efficiency, the clutch may be cooled as disclosed in the pending application for United States Letters Patent of C. D. Barron, Ser. No. 19,601 filed Mar. l6, 1970. The position sensor referred to above is adapted to cause a change in the fluid pressure acting on the slip clutch, and is preferably made in accordance with the disclosure of the pending application for United States Letters Patent of C. C. Barron, Ser. No. 19,564, filed Mar. 16, 1970.

This invention possesses many other advantages, and has other purposes which may be made more clearly apparent from a consideration of a form in which it may be embodied. This form is shown in the drawings accompanying and forming part of the present specification. It will now be described in detail, for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective, generally illustrating an offshore well drilling platform having a material handling crane and a work boat, to which the displacement control system of the invention has been applied;

FIG. 2 is a diagrammatic view illustrating the displacement control system, as applied to the crane and work boat of FIG. 1;

FIGS. 30 and 3b, together, constitute a schematic diagram of the displacement control system, FIG. 3b being a downward continuation of FIG. 3a;

FIG. 4 is a view partly in elevation and partlyin longitudinal section showing a slip clutch for use in the control system;

FIG. 5 is a longitudinal section, showing a typical line position sensor operable by the load position sensing line and by the boat reference position sensing line; and

FIG. 6 isa longitudinal section, showing the computing relay which compares the position responsive signals from the position sensors.

DESCRIPTION OF THE PREFERRED EMBODIMENT As seen in the drawings, with reference first to FIG. 1, an offshore well drilling platform P is shown, elevated above the water, and having a derrick D from which well drilling operations may be conducted. At a corner of the platform P is a typical crane C, mounted so that its boom B may be swung to a position above a work boat or other vessel V, onto or from the deck of which a load L is to be moved by the hoist means H of the crane C. As seen in FIG. 2, the hoist means H, includes a hoist line or cable 10 which is wound on a winch drum W and which extends over the usual block 1 1, at the free end of the boom B, and is reaved through a traveling block 12 which has a load-engaging hook 13 by which the load L is suspended.

The winch W is driven by a power source or motor M which has a chain drive connection with a clutch drive sprocket 21. A slip clutch SC, the details of which are shown in FIG. 4, is adapted to drive the winch W through a counter-shaft 22 and a chain and sprocket drive 23.

In general, the displacement control system operates to control the slip clutch SC to estabilsh its torque transmitting capacity, as will be later described. More particularly, the system includes first position sensing means LP for sensing the position of the load L relative to the boom B and second position sensing means RP for sensing the position of the vessel V relative to the boom. These position sensing means are exemplified in FIG. 5 and each of them produces an output signal that is supplied to a computing relay or transmitter R, the details of which are shown in FIG. 6, where the signals are compared and equated with a signal derived from a speed responsive or tachometer device S driven by the winch W, to supply an output signal to a proportional controller PC which supplys an output signal to the slip clutch SC that is a function of the load position signal and the signal derived from the computer R and which determines the torque transmitting capacity of the slip clutch SC.

The load position sensing means LP, as seenin FIG. 2, comprises a cable or line 25, the free end 26 of which is connected to the traveling block 12. The line passes over a suitable pulley 27 carried by the crane boom B, and thence to a line position sensing unit SU having a pulley 28. A pair of guide pulleys 29 maintain drive friction between the line 25 and the pulley 28. The line 25 is spooled on a spring rewound drum 30 which takes up the line 25 or plays the line out as the traveling block 12 and, hence, the load L are raised and lowered. Such motion of the line 25 adjusts the output signal supplied from the sensing unit SU to the computthe pressure controller Like the sensing means LP, the sensingmeans RP includes a pair of line guiding pulleys 29 and a spring rewound spool 30 for taking up the line 31 and playing out the line as the vessel V moves vertically relative to the crane, the line 31 adjusting its sensing unit to vary the pressure signal supplied to the computing relay or transmitter R, to affect the pressure signal transmitted to the controller PC and, thus, to the clutch SC, the torque transmitting capacity of which is varied by the system.

The clutch C, as best seen in FIG. 4, is associated with an end 33 of the counter-shaft 22, and the drive chain 20 engages the sprocket 21 which is revolvable relative to the shaft end 33 on bearings 33a. Affixedto the sprocket 21, is a disc 34 which is in turn affixed by fasteners 35 to the outer periphery of the back-up plate 36 of the slip clutch means SC.

This slip clutch means SC includes an outer annular body 37 to which an annular flange 38 is connected by fasteners 39 in opposed relation to the plate 36. Internally thereof, the body 37 has a splined connection 40 with the outer periphery of an axially shiftable clutch pressure plate 41. Between the clutch plates 36 and 41 is a clutch friction disc 42 having friction facing 43 on opposite sides thereof and having, as at 44, a splined connection with a hub 45 which is disposed upon the shaft end 33 and is keyed thereto by a key 46. Thus, rotation from the sprocket 21 will be transmitted to the tensioning hoist shaft 22 when the slip clutch means SC is engaged to transmit rotation from the clutch body 37 and its plates 36 and 41 to the friction disc 42.

Engagement of the slip clutch means SC is accomplished by an annular expansible actuator tube 47 having an air inlet 48. The actuator tube 47 engages an annular body of insulating material 49 interposed between the tube 47 and the clutch pressure plate 41. Each of the clutch plates 36 and 41 has a number of annular, radially spaced and concentric coolant passages 36a and 41a to which a coolant is supplied to dissipate the heat of friction caused by slippage of the clutch SC. These passages 36a and 41a are defined respectively between the clutch plates and a wear disc 36 carried by the plate 36b and a wear disc 41!; carried by the plate 41, the friction material on the friction disc 42 being engaged with the wear discs 36b, 41b.

Such cooled, slip clutches are well known, and generally areprovided with a coolant circulating system including a stationary coolant connector 51 through which coolant flows to and from a rotary connector 52 which is connected, as by fasteners 52a, to the clutch flange 38 and which has conduit means 53 for supplying coolant to the passages 36a and 41a, as well as conduit means for the return flow of coolant to the connector 51 and thence to a heat exchanger. Preferably, in order to more effectively cool the clutch, it is constructed in accordance with the aforementioned application for patent. In addition, the rotary connector 52 provides a connection for air conduit means 54 which leads to the air inlet 48 for the clutch actuator tube 47 from a stationary air inlet fitting 55. As is well known, the torque transmitting capacity of such slip clutches varies with the pressure of air in the actuator tube 67.

Thus, the tension applied to the line will be determined by the magnitude of the air pressure supplied to the actuator tube 47 through the coupling 55 under the control of the computing relay R, as will be more fully described below.

The typical and preferred line position sensing unit SU of the sensing means LP and RP is shown in greater detail in FIG. 5. It comprises an elongated housing 81 having at one end a closure or cap 82 and having at the other end an assembly which provides an air inlet or supply port 84, an outlet 85 for a controlled air pressure signal, a port 86 for bias pressure fluid, and a port 87 communicating with the atmosphere.

Included within the assembly are actuator means generally denoted at 88, fluid pressure responsive piston means 89 operatively connected to the actuator means 88, orifice means 90 operable in response to the application of fluid pressure to the piston means 89 and to the application of force from the actuator means 88 for opening and closing the orifice means 90, and combined inlet and outlet valve means 91 for controlling the flow of air from the supply port 84 to the outlet port 85 and for controlling the exhaust of air from the outlet port 85 to the atmosphere through the port 87.

In general, it is the purpose of the position sensing pneumatic control device to regulate the output signal pressure to a constant value which is determined by the net force applied to the piston means 89, whereby the orifice means 90 is either opened or closed for a period sufficient to balance the piston means 89, so that the pressure drop through the orifice means 90 remains constant, resulting in a constant output signal pressure at the port 85 which leads to the computer relay or transmitter R, as will be later described.

More particularly, the actuator means 88 comprises a shaft 92 which extends longitudinally of the housing 81 and has an end 93 which extends axially from the end cap 82 through a suitable bearing 94 and a suitable seal 95. Disposed upon the shaft 92 within the housing 81 is a spring seat 96 having a reduced central section 96 on which is piloted the upper end of a coiled compression spring 98. The shaft 92 is threaded as at 99, and the spring seat 96 and the reduced pilot portion 96 thereof are complementally threaded, whereby rotation of the shaft 92 will effect longitudinal movement of the spring seat 96 on the shaft, since the seat 96 is held against rotation by a key 100 carried thereby and extending into a lateral slot 101 in the housing 81. At its inner end, the spring 98 seats on a spring seat 103 having a reduced pilot portion 104. This spring seat 103 is connected by fasteners 105 to the circular upper body portion 106 of the piston 107 of the piston means 89, the seat 103 and the body 106 being held in axially spaced relation by tubular spacers 108 interposed therebetween and through which the fasteners 105 extend. The lower end of the shaft 92 extends through the seat 103 and is joumalled in a bearing 109 which is mounted in a supporting spider 110 having circumferentially spaced openings 111 to accommodate the spacers 108, whereby the piston means 89 is axially movable.

The assembly also comprises, in addition to the spider 110, an annular spacer 112, an annular cylinder 113 for the piston 107 and an annular cylinder 14 which houses a piston 115, an annular body 116 containing the nozzle means 90, and an end member 117. The spider 110, spacer 112, cylinders l 13 and 1 14, annular body 116, and end member 117 are interconnected together and to the cylindrical body 81 by tiebolts or the like, requiring no illustration.

Between the spacer 112 and the cylinder 113 is clamped the outer marginal portion of a diaphragm 119, and between the cylinder 113 and the cylinder 114 is clamped the outer marginal portion of another diaphragm 120. Still another diaphragm 121 has its outer marginal portion clamped between the cylinder 114 and the annular body 116. In the illustrative embodiment, the body portion 106 of the piston 107, as well as the piston 107 and the piston are interconnected by a stem 122 having an enlarged head 123 at one end which clamps the inner periphery of the diaphragm 121 against the adjacent portion of the piston 1 15, and a nut 124 is threaded onto the other end of the stem 122 to eflectively clamp the piston 107, including its upper body portion 106, and the piston 115 together. The inner periphery of the diaphragm 119 is likewise clamped between the upper body portion 106 and the piston 107, and the inner periphery of the diaphragm is clamped between the piston 107 and the piston 115. Thus, the piston means 89 comprises both the piston 107 and the piston 115. More particularly, the piston 107 has an enlarged portion 125 which is exposed to the pressure in a chamber 126 provided in the cylinder 113 between the diaphragms 119 and 120. The piston 115 is exposed to the pressure in a chamber 127 provided in the annular body 116 across substantially the entire cross-sectional area of the piston 1 15. Within the cylinder 114, the piston 115 is disposed in a chamber 128 which is vented to the atmosphere through radial ports 129.

Interposed between the annular body 116 and the end member 117, and clamped at its outer margin is a double diaphragm assembly including an upper diaphragm 130 and a lower diaphragm 131 spaced apart by an outer marginal spacer 132 in which is formed one or more of the radial ports 87, previously referred to, which communicate the space between the dia'phragms 130 and 131 with the atmosphere. In the annular body 116 above the upper diaphragm 130 is a chamber 134 and centrally of the body 116 is a threaded bore having therein a nozzle 136 of the nozzle means 90, the port through which communicates with the chamber 134, and the outlet of which is opposed by a nozzle seat 137 suitably carried by the lower end of the stem 122. Air is supplied to the chamber 134 and thence to the nozzle 136 from the supply port 84 through a passage 138 which extends through the margin of the diaphragms 130 and 131 and the spacer 132 and connects with a passage 139 leading into the chamber 134. Disposed in the passage 139 is a flow restrictor 140 having a reduced passage therethrough. This flow restrictor is replaceable through an opening in the body 116 which is closed by a threaded closure plug 141. At the outer side of the diaphragm 131 in the end member 117 is a chamber 142 which communicates with the outlet port 85. The outlet port 85 also communicates through a passage 143 with the chamber 127 in the body 116 below the diaphragm 121.

The inlet and outlet valve means 91, previously referred to, includes a valve seat 144 carried by a plate 145 below the diaphragm 131 and having a valve port 146 leading from the outlet chamber 142 into the space between the diaphragms 13D and 131. A coiled compression spring 145a is provided beneath the plate 145 which applies a normal inward bias to the diaphragm 131 and to the outlet valve seat 144. A valve stem 147 is reciprocably mounted in a port 147a in the end member l 17, which port leads from the inlet 84 to the outlet 85. The stem is normally biased inwardly by a coiled compression spring 148 which seats in a plug 149 in the end member 117 and acts inwardly on a spherical valve head 150 to bias the same against an inlet valve seat 151.

As previously indicated, the position sensing pneumatic control device functions to' regulate the output signal pressure at the port 85 to a value which is proportional to sensed movement. Accordingly, the outer end 93 of the shaft 92, in the illustrative embodiment, has mounted thereon the sheave or roller 28 which is engaged by the sensing cable or line 25 or 31, of the sensing means LP and RP, to effect rotation of the shaft 92 in response to relative movement between such line 25 or 31 and the sensing unit SU. Movement of thesensing line is transmitted to the shaft 92 to effect rotation of the latter in one direction or the other depending upon the direction of movement of the line 25 or 31, which depends on the direction of relative movement of the crane, the load, and the vessel. It is apparent that rotation of the shaft 92 in one direction or the other will impose more or less compression on the spring 98 to provide more or less force acting on the piston means 89 which will either cause the nozzle seat 137 to close the nozzle 136 or to open the nozzle 136 for communication with the chamber 127, and hence the discharge or signal output port 85. Such spring force is opposed by the pressure of air in the chamber 127 acting on the cross-sectional area of the piston 115 and the pressure of fluid in the chamber 126 acting on the effective area of the piston 107. Thus, the fluid admitted through the port 86 to the chamber 126 may be supplied from a remote set point or control point to modify operation of the sensing unit SU so that the signal output pressure is at a desired level, as will be later described in respect of the sensing unit of the reference position sensing means RP, or the chamber 126 may be exposed to atmosphere.

With the foregoing details in mind, the operation of the motion sensor is such that the spring 98 is operative to apply a variable force in a direction tending to move the piston means 89 downwardly. Opposing the force derived from the actuator means is the force derived from the application of pressure either atmospheric or from a remote set point to the bias chamber 126, which pressure is effective over the area of the enlargement 125 of the piston means 89 to provide a force tending to move the piston means 89 upwardly. Also providing force tending to move the piston means 89 upwardly is the pressure in the piston chamber 127 which acts upon the piston 1 15 of the piston means 89, the other side of the piston 115 being exposed to the atmosphere in the chamber 128.

The effective signal outlet pressure in the piston chamber 127 is a function of the inlet pressure and the passage of air from the inlet 84 through the flow restrictor 140 into the pilot pressure chamber 134 and the passage of air from the pilot pressure chamber 134 through the orifice means 136, as indicated by the arrows, into the piston chamber 127. When the device is in the condition shown in FIG. 5, the effective signal outlet pressure at the outlet 85 is the same as that in the piston chamber 127, and under the condition shown the pressure at the outlet 85 will remain constant, unless the force derived from the actuator means 88 is varied, or the force derived from the remote set point pressure is varied, as will be later described. means 88 is varied, or the force derived from the remote set point pressure is varied, as will be later described.

Assuming that the force derived from the actuator means tending to shift the piston means 89 downwardly is reduced, the net force acting on the piston means will cause the piston means to move upwardly, allowing greater flow from the pilot pressure chamber 134 into the piston chamber 127. Such action will result in an instantaneous decrease in the pilot pressure in the chamber 134. As a consequence, pressure applied to the diaphragm 131 and the force of the spring 145a will move the exhaust valve seat 144 upwardly away from the end of the valve stem 147, to allow the greater exhaust of fluid pressure from the outlet chamber 142 and the piston chamber 127 through exhaust port 87, until the device again assumes the condition shown in FIG. 5 at which valve means 91 is at equilibrium and the necessary volume of air is permitted to flow through the port 146. At this time, the pressure at the outlet 85 will again be stabilized at a value determined by the fluid pressures acting on the actuator means 88 and the decreased spring force of the spring, and the signal outlet pressure will be at a lower value.

Assuming that the force derived frmom the actuator means tending 'to move the piston means 89 downwardly is increased, overcoming the effect of the signal outlet pressure in the chamber 127, then the orifice closure disc 137 will engage the end of the orifice means 136, thereby shutting off the passage of air from the pilot pressure chamber 134 into the piston chamber 127. Under these circumstances, the pilot pressure in the pilot chamber 134 will build up, forcing the diaphragm 130 and the diaphragm 131 downwardly, thereby unseating the valve 150, so that inlet pressure will transfer through port 147a of the inlet-outlet valve means 91, resulting in an increase in the signal outlet pressure in the outlet chamber 142 and in the piston chamber 127 which will be effective to again condition the apparatus as shown in FIG. 5, so that the pressure at the outlet 85 again remains constant, but greater.

It will now be understood that variation of the remote set point pressure in the chamber 126 will have the same effect as variation of force derived from the actuator means. In other words, as the remote set point pressure is increased, the force tending to move the piston means 89 upwardly will also be increased, but if the remote set point pressure is decreased, the force tending to move the piston means 89 upwardly will be decreased.

The supply of air to the chamber 126 of the unit SU of the reference position sensing means RP, through the port 86 is shown in FIG. 30, as being via a conduit 86a leading from a suitable vavle 86b which controls the pressure derived from a source conduit 86c which leads from a suitable pressure source, not shown. The outlet port of the unit SU is in communication with a conduit 85a which leads to the computer means R.

On the other hand, the chamber 126 of the unit SU of the load position sensing means LP. communicates with LP, through the port 86, unless a bias pressure other than atmosphere pressure is desired to modify the operation of the system. In any case, the outlet 85 of this unit SU is connected by a conduit 85b to the proportional controller PC, later to be described, and to the computing relay or transmitter R.

The computer relay or transmitter R, as seen in FIG. 6, comprises a support 200 adapted to be mounted at a suitable location. Carried by the support 200 is an end cup 201 having a marginal flange 202 for connecting the cup 201 with an assembly which comprises a stack of discs 203, 204, 205, 206 and 207 and a body 208, all connected at the outer peripheries by a suitable number of tie bolts, one of which is shown at 209. The disc 203 includes a rigid central section 203 and a flexible annular diaphragm 203" supporting the central section. Each of the discs 204, 205, 206 and 207 correspondingly comprises a rigid central section 204' to 207' and an annular diaphragm 204 to 207". Intermediate the discs 203 to 207 are annular, outer peripheral spacers 210 and central spacers 211. The outer spacers 210 are connected in the assembly by the tie bolts 209. The central spacers 211 are interconnected at the respective central sections 203' to 207 by a pin 212 having a head 213 at its lower end and a nut 214 at its upper end for clamping the central disc sections and central spacers together.

Fluid under pressure, say air, is supplied to the computer means R above and below the stack of diaphragms and between the diaphragms from various sources, whereby to provide an output pressure signal which is a function of the various input signals and the constant force of an adjustable coiled spring K which is disposed in the cap 201 and seats, at one end, on a seat 215 above the disc section 203' and at the other end on a spring seat 216 carried by an axially shiftable adjuster pin 217. The pin 217 is shiftable by an adjuster screw 218 threaded in a nut 219 which is suitably affixed to the support 200. Below the disc 207 is another 'coiled spring K which seats at one end in a seat 208' and engages at its other end beneath the disc section 207' in opposition to the spring K. Thus, the spring K is adjustable to provide a selected force on the stacked disc sections 203 to 207', determined by the relationship between springs K and K.

Air pressure is supplied to a chamber RPl in the cup 201, from the position sensor unit SU of the reference position sensing means RP via conduit 850, by suitable means, such as an inlet fitting 220, to provide a downward force on the effective piston area of the central section 203' of disc 203. In order to increase the magnitude of the force derived from air pressure supplied to the computer R from this position sensor unit SU via conduit 85a, a branch conduit from conduit 85a leads to a chamber RP2 defined between the diaphragms 203" and 204", say through a pressure inlet 221, so that such pressure also acts downwardly on the effective annular piston area of the central section 204' of the disc 204, which extends radially beyond the spacer 211 thereabove.

Below the annular piston area of the disc section 204' is a chamber LP having an inlet 222 to which pressure fluid is supplied, via conduit 85b, at a value determined by the sensing unit SU of the load position sensing means LP, the pressure in chambe LP acting upwardly on the effective annular piston area of the disc section 204' in opposition to the downward force derived from pressure in the chambers RP1 and RP2.

Between the discs 205 and 206 is defined a pressure chamber S to which air is supplied through an inlet 223 via a conduit 2230, at a pressure determined by the speed of rotation of the winch W, under the control of the speed responsive means S, previously referred to, which may be a typical Foxboro Type 16A pneumatic speed transmitter which produces at conduit 223a an air signal derived from a source 223k and of a magni tude determined by the speed of rotation of the winch W. Other pneumatic speed transmitters are well known. The disc section 206' provides an annular piston area projecting radially outwardly of the spacer 21 1 thereabove, this piston area being responsive to pressure in chamber S to provide a downward force. Below the disc section 206 is another chamber T exposed via a port 224 to atmosphere but to which air may be supplied at a pressure determined by the tension on the load supporting line L. Such pressure acts upwardly on the effective annular piston area of the disc section 206.

Below the disc 207, and in the body 208, is a chamber X which constitutes an output chamber communicating with an outlet port 225 via porting 226. The pressure in the chamber acts upwardly on the lower disc section 207', and this pressure is derived from an inlet conduit 227a connected to an inlet port 227, and under the control of the computer R, a signal istransmitted to the proportional controller PC, as will be later described.

Interposed between the body 208 and an end member 228 having the ports 225 and 227 therein, and clamped at its outer margin, is a double diaphragm assembly 229 including an upper diaphragm 230 and a lower diaphragm 231 spaced apart by an outer marginal spacer 232 in which is formed one or more radial outlet ports 232a, which communicate the space between the diaphragms 230 and 231 with the atmosphere. In the body 208 above the upper diaphragm 230 is a threaded bore having therein a nozzle 236, the port through which communicates with the chamber X, and the outlet of which is opposed by a valve head 237 suitably carried by the lower end of the stem 212. Air is supplied to the chamber 234 and thence to the nozzle 236 from the supply port 227 through a passage 238 which extends through the margin of the diaphragms 230 and 231 and the spacer 232 and connects with a passage 239 leading into the chamber 234. Disposed in the passage 239 is a flow restrictor 240 having a reduced passage therethrough. This flow restrictor is replaceable through an opening in the body 208 which is closed by a threaded closure plug 241. At the underside of diaphragm 231 in the end member 228 is a chamber 242 which communicates with the output port 225. The output port 225 also communicates through the passage 226, previously referred to, with the chamber X in the body 208 below the piston or disc section 207.

lnlet and outlet valve means are provided to control the admission of fluid from the inlet 227 to the chamber 242 and the exhaust of such fluid through the vent port 232a. This valve means includes a valve seat 244 carried by a plate 245 below the diaphragm 231 and having a valve port 246 leading from the outlet chamber 242 into the space between the diaphragms 230 and 231. A coiled compression spring 245a is provided beneath the plate 245 and applies a normal upward bias to the diaphragm 231 and to the outlet valve seat 244. A valve stem 247 is reciprocably mounted in a port 247a in the end member 228, which port leads from the inlet 227 to the outlet chamber 242. Th stem is normally biased inwardly by a coiled compression spring 248 which seats in a plug 249 in the end member 228 and acts inwardly on a spherical valve head 250 to bias the same against an inlet valve seat 251.

As previously indicated, the computer means R functions to regulate the output signal pressure at the port 225 to a value which is proportional to the input signals from the sensing units SU, as well as the input signal representing speed of the drum W, and in addition, the computer may be adjusted to modify the output pressure by varying either the effective constant force of spring K or the reference set point pressure in the chamber RP. Thus, as will be understood, the output pressure in chamber X is determined by the various pressures in the various chambers RPl, RP2, LP, S and T, acting on the various piston areas of the discs 203 to 207. The equation may be stated;

where RP] and RPZ are the pressure derived from the reference line position sensing means RP tending to close the nozzle 236, LP is the pressure derived from load position sensing means LP tending to open the nozzle 236, S is the pressure derived from the speed of the drum W tending to close the nozzle 236, T is the atmospheric pressure tending to open the nozzle 236, and K is the spring constant.

The effective signal outlet pressure in the outlet chamber 242 is a function of the reduction in the inlet pressure caused by the passage of air from the inlet 227 through the flow restrictor 240 into the pilot pressure chamber 234, and the reduction in pressure resulting from the passage of air from the pilot pressure chamber 234 through the orifice means 236, as indicated by the arrows, into the pressure chamber X. When the device is in the condition shown in FIG. 6, the effective signal outlet pressure at the outlet 225 is the same as that in the chamber X, and, under the condition shown, the pressure at the outlet 225 will remain constant, unless the force derived from any of the position sensing means LP or RP, the tachometer S, or the reference pressure at chamber T is varied, and, accordingly as will be later more fully described, the actuatinG pressure supplied to the clutch SC will remain constant.

Assuming that the force tending to shift the stacked disc sections causes the valve head 237 to move upwardly allowing greater flow from the pilot pressure chamber 234 into the chamber X, such action will result in a decrease in the pilot pressure in the chamber 234. As a consequence, pressure applied to the diaphragm 231 and the force of the spring 245a will move the exhaust valve seat 244 upwardly and off of the end of the valve stem 247 to allow the exhaust of fluid pressure from the outlet chamber 242 and the chamber X through exhaust port 232a between the diaphragms 230 and 231, until the device again assumes the condition shown in FIG. 6 at which the exhaust valve port 246 is again closed. At this time, the pressure at the outlet 225 will again be stabilized at a lower value, determined by the change in forces acting on the stack of disc sections 203' to 207'.

Assuming that the net force tending to move the stacked discs 203' to 207' downwardly is increased, overcoming the effect of the signal outlet pressure in the chamber X, then the orifice valve 237 will close the orifice means 236, thereby shutting off the passage of air from the pilot pressure chamber 234 into the chamber X. Under these circumstances, the pilot pressure in the pilot chamber 234 will build up, forcing the diaphragm 230 and the diaphragm 231 downwardly, thereby unseating the valve 250, so that inlet pressure will transfer through port 2470 of the inlet-outelt valve means, resulting in an increase in the signal outlet pressure in the outlet chamber 242 and in the chamber X, which will be effective to again condition the apparatus as shown in FIG. 6, so that the pressure at the outlet 225 again remains constant, but greater.

At this point, it will be understood that the pressure in the chambers RPl and RPZ of the computing relay R is determined not only by the position of the reference sensing line 31, resulting in the transmitting of a pressure from the sensing unit SU of the reference position sensing means RP to the chambers RPl and RPZ related to reference position line movement, but also by the variable bias pressure in chamber 126 of this sensing unit supplied via conduit 86a, resulting in more or less force applied to the piston means 89 to oppose the force of the spring 98. Thus, by manipulating the supply valve 86b, the outlet signal pressure supplied from the unit SU of the reference position sensor RP, is adjusted to modify the outlet signal pressure in the chamber X of the computing relay R, so that the signal supplied from the latter to the proportional controller is varied to adjust the clutch SC and move the load relative to the vessel V.

A conduit 300 leads from the outlet port 225 of the computing relay R to the control pressure inlet 301 of the pressure controller PC, of a conventional type, adapted to control the pneumatic pressure at an outlet 302 supplied from a suitable source (not shown) through an inlet 303, whereby, as will be later described the slip clutch SC is adapted to apply a controlled constant torque to the drum W which is a function of the output signal pressure of the computer or transmitter means R.

More particularly, the controller PC may be Model 50 Controller of Moore Products Co., of Spring House, Pennsylvania or a Model 2516 Controller of Fisher Governer Company of Marshalltown, Iowa, as examples, the controller, generally shown in FIG. 3b, being the latter and more specifically illustrated in Bulletin D-2506A of that company.

The controller PC is supplied a reference pressure at an inlet 304 from the conduit b connected to the outlet from the sensing unit SU of the load position sensing means LP, the same reference pressure being supplied to the chamber LP of the computer or transmitter means R. The pressure signal from the chamber X of the computer R is admitted to a bellows 307 of the controller PC which acts downwardly on a plate 308. Pressure supplied to the inlet 304 from the load position sensing unit SU causes an increase in pressure in a bellows 309 which is opposed to the bellows 307 and acts upwardly on the plate 308. The position of the plate 308 relative to a nozzle 310 to which controlled fluid pressure is supplied from the source inlet 303, is determined by the difference in pressures in the bellows 307 and 309. If the output pressure from the load position sensing means LP increases, the pressure increases in bellows 309 causing the plate 308 to move closer to the nozzle 310, restricting flow through the nozzle to cause an increase in the pressure in a chamber 311 of a control valve 312, causing an increased downward force on a diaphragm assembly comprising spaced diaphragms 313 and 314, which carries a valve seat 315, the passage through which communicates with the atmosphere through a port 316 between the diaphragms 313 and 314. The valve seat 315 engages and pushes downwardly, under the circumstances now being described, on an inlet and outlet valve having a head 317 for closing the exhaust passage through the valve seat 315 and a head 318 which is moved away from a seat 319 to allow increased supply pressure into the valve outlet chamber 320 which acts on the diaphragm 314 until the valve seat 315 is again moved upwardly to allow return upward movement of the inlet-outlet valve head 318 towards its seat.

During the same time that pressure is increasing in the chamber 320, such pressure is supplied to the outlet 302, and, thus, to the clutch SC via a conduit 325, as well as to an adjustable proportioning valve 321 and, depending on the adjustment of the latter, to an adjustable re-set control valve 322 which controls the build up of pressure in a bellows 323. This bellows 323 acts downwardly on the plate 308 tending to move the latter away from the nozzle 310 to decrease pressure at the outlet 302 and in control valve chamber 320, and is opposed by the upward action of a bellows 324 to which pressure is supplied from the valve 322 at a slower rate, depending on the adjustment of the valve 322, until the plate 308 is moved toward the nozzle to again increase pressure at the outlet 302 and in the valve chamber 320.

If a change in the system causes a decrease in pressure at the inlet 304 to the controller PC, then, the reverse action will occur in the controller, the tendency being in either case to attempt to return to a preestablished, constant pressure at the outlet 302, which pressure is a function of the outlet pressure from chamber X of the above-described computer means R and the signal pressure from the sensing unit SU of the load position sensing means LP.

The outlet pressure from the controller means PC is supplied via the conduit 325 to cause actuation of the clutch SC, but preferably a typical booster 326 is employed, whereby the actual pressure source (not shown) for the clutch includes an inlet to the booster 326 from a relatively high pressure source, and the pressure in conduit 325 acts on the usual pilot valve of the booster, so that the outlet 328 of the booster is at a greater pressure than the signal pressure from the controller PC. In addition, it is preferred that a selector valve 329 be provided, so that the air connector 55 of the clutch SC may be connected either to the booster outlet 328 or, alternatively, to a separate source conduit 330 including a manual control valve 330a for operating the clutch SC independently of the control system.

I For convenience, a gauge panel G is preferably provided, as seen in FIG. 3a, whereby to indicate the effective pressures determined by the reference line and load line position sensing means RP and LP, respectively, and the ultimate clutch actuating pressure supplied to the slip clutch SC, such gauges being desig- 14 nated by the legends "REF. POS.", LOAD POS.", and CLUTCH.

The REF. POS. gauge is connected to the output of the sensing unit SU of the reference position sensing means RP by a conduit 400 which joins with the conduit a leading to the computer chambers RP] and RP2. The LOAD POS. gauge is connected by a conduit 401 to the conduit 85b which also leads to both the inlet 304 of the controller PC and to the chamber LP of the computer or transmitter R. The CLUTCl-l" gauge is connected by a conduit 406 with the air inlet connector 55 of the clutch SC and the outlet 328 of the pneumatic booster 326. Other gauges may be employed if desired to show other pressures, such as the pressure derived from the speed of the winch W, and the bias pressure supplied to the sensing unit SU of the reference line position sensing means RP.

From the foregoing, it is seen that the operation of the present invention clearly involves the controlling of the slip clutch drive means for the winch drum W to apply a tension to the line L, controlled such that the tension is maintained substantially constant at a value established by the bias pressure supplied to the bias chamber 126 of the reference position sensing means RP, but the air pressure supply to the clutch is, in the automatic mode, controlled by changes in load line position or reference line position sensed by the sensing means LP and RP, respectively, whereby, when the vessel V moves relative to the crane C, a reference signal proportional to the movement is supplied to the chambers RPl and RP2 of the computer R, varying the output signal pressure in the chamber X of the computer which is transmitted to the inlet 301 of the proportional controller PC, which varies the actuating pressure supplied to the actuator of the clutch SC; to cause the load to move, thus operating the load position sensing means LP until a change in the pressure supplied to chamber LP of the computer R equals the pressure change caused by movement of the reference line. Thus, the load is caused to move substantially synchronously with the vessel V, unless the bias pressure supplied to the chamber 126 of the sensing unit SU of the reference line position sensing means RP is varied at the valve 86b, to move the load in one direction or the other relative to the vessel V.

The speed signal pressure transmitted to the chamber S of the computer means R is selected at some constant value when the winch is stationary, and the speed responsive means produces an increasing pressure signal as the velocity of the load increases upwardly and a decreasing pressure signal as the velocity of the load increases downwardly. During load movement, the transmitter S continuously supplies a changing pressure to the chamber S of the computer R, which changes the computer output signal to the controller PC to assist in controlling overshooting the end points of the load motion, and, it is apparent that the speed circuit may be adjusted to limit load speed to a predetermined value in either direction, by limiting the increase or decrease in the speed signal pressure. In addition, the doubling of the effect of the reference line position pressure signal supplied to the computer means R in a pair of chambers RPl and RP2, causes the signal supplied to the controller PC to be greater than would be the case if the signal to the controller at the reference inlet 301 were supplied directly from the sensing unit SU of the reference line position sensing means RP.

It will also be understood, that if load control is desired, to limit load on the crane, a load responsive signal may be transmitted to the chamber T of the computer means R to produce an output signal which is determined by load on the line adding a force to the computer means R supplementing the forces derived from load movement.

I claim:

1. Hoist apparatus for use in moving a load between relatively vertically movable locations, comprising: a winch having a load supporting cable connectable to the load, means for operating said winch to take up and play out said cable including slipping drive means adjustabie to apply more or less torque to said winch to raise and lower said load, load position sensing means for sensing vertical movement of said load, reference position sensing means for sensing relative vertical movement of said locations, and control means for adjusting said slipping drive means operable by said load position sensing means and said reference position sensing means to cause said load to move vertically synchronously with the relative movement between said locations, said control means including means operable to cause said load to be moved between said locations, each said position sensing means including a body having an inlet chamber and an outlet chamber, a piston chamber communicating with said outlet chamber, a piston chamber communicating with said outlet chamber, piston means having a surface exposed to pressure in said piston chamber, actuator means for applying a force to said piston means in opposition to the force applied to said piston means by fluid pressure in said piston chamber, a pair of diaphragms defining an exhaust chamber therebetween, one of said pair of diaphragms having an exhaust valve port leading from said outlet chamber to said exhaust chamber, a pilot pressure chamber, the other of said pair of diaphragms being exposed to pressure in said pilot pressure chamber, a passage having a flow restrictor therein leading from said inlet chamber to said pilot pressure chamber, a nozzle having a passage leading from said pilot pressure chamber to said piston chamber, a closure forsaid nozzle passage carried by said piston means and movable be tween positions opening and closing said nozzle passage upon movement of said piston means in opposite directions, and inlet and outlet valve means for controlling the direct flow of fluid from said inlet chamber to said outlet chamber and from said outlet chamber through said exhaust port in response to variations in the pressure in said pilot pressure chamber.

2. The apparatus as defined in claim 1 wherein said actuator means includes a compression spring acting on said piston means, a spring seat connected to said piston means and engaged by one end of said compression spring, a second spring seat engaged by the other end of said compression spring, and means responsive to movement of the member whose movement is to be sensed to move said second spring seat toward and away from said spring seat connected to said piston means to vary the force for moving said piston means in said one direction as a function of the movement of the member whose position is to be sensed. 

1. Hoist apparatus for use in moving a load between relatively vertically movable locations, comprising: a winch having a load supporting cable connectable to the load, means for operating said winch to take up and play out said cable including slipping drive means adjustable to apply more or less torque to said winch to raise and lower said load, load position sensing means for sensing vertical movement of said load, reference position sensing means for sensing relative vertical movement of said locations, and control means for adjusting said slipping drive means operable by said load position sensing means and said reference position sensing means to cause said load to move vertically synchronously with the relative movement between said locations, said control means including means operable to cause said load to be moved between said locations, each said position sensing means including a body having an inlet chamber and an outlet chamber, a piston chamber communicating with said outlet chamber, a piston chamber communicating with said outlet chamber, piston means having a surface exposed to pressure in said piston chamber, actuator means for applying a force to said piston means in opposition to the force applied to said piston means by fluid pressure in said piston chamber, a pair of diaphragms defining an Exhaust chamber therebetween, one of said pair of diaphragms having an exhaust valve port leading from said outlet chamber to said exhaust chamber, a pilot pressure chamber, the other of said pair of diaphragms being exposed to pressure in said pilot pressure chamber, a passage having a flow restrictor therein leading from said inlet chamber to said pilot pressure chamber, a nozzle having a passage leading from said pilot pressure chamber to said piston chamber, a closure for said nozzle passage carried by said piston means and movable between positions opening and closing said nozzle passage upon movement of said piston means in opposite directions, and inlet and outlet valve means for controlling the direct flow of fluid from said inlet chamber to said outlet chamber and from said outlet chamber through said exhaust port in response to variations in the pressure in said pilot pressure chamber.
 2. The apparatus as defined in claim 1 wherein said actuator means includes a compression spring acting on said piston means, a spring seat connected to said piston means and engaged by one end of said compression spring, a second spring seat engaged by the other end of said compression spring, and means responsive to movement of the member whose movement is to be sensed to move said second spring seat toward and away from said spring seat connected to said piston means to vary the force for moving said piston means in said one direction as a function of the movement of the member whose position is to be sensed. 